JP2021190726A - Zoom lens and imaging apparatus - Google Patents

Abstract

To provide: a zoom lens that has anti-vibration performance, is advantageous for miniaturization and weight reduction, and maintains good optical performance; and an imaging apparatus equipped with this zoom lens.SOLUTION: A zoom lens includes: a first lens group with positive refractive power; a second lens group with negative refractive power; an intermediate group with positive refractive power; and a subsequent group with negative power arranged in this order from a most object side to an image side. The first lens group moves during zooming. The second lens group includes: a second lens group front group which is immovable during image blur correction; and an anti-vibration group with negative refractive power that moves during the image blur correction in this order from the object side to the image side. The zoom lens satisfies a predetermined conditional expression.SELECTED DRAWING: Figure 1

Description

The techniques of the present disclosure relate to zoom lenses and image pickup devices.

As a zoom lens applicable to an image pickup device such as a digital camera and a video camera, the lens systems described in the following Patent Document 1 and the following Patent Document 2 are known.

Japanese Unexamined Patent Publication No. 2019-053122 Japanese Unexamined Patent Publication No. 2015-191008

In recent years, there has been a demand for a zoom lens that has anti-vibration performance, is compact and lightweight, and maintains good optical performance.

The present disclosure has been made in view of the above circumstances, and is a zoom lens having anti-vibration performance, advantageous for miniaturization and weight reduction, and maintaining good optical performance, and an image pickup equipped with this zoom lens. The purpose is to provide the device.

The zoom lenses of the present disclosure include a first lens group having a positive refractive force and a second lens group having a negative refractive force continuously arranged in the first lens group in order from the object side to the image side. , An intermediate group having a positive refractive power including at least one lens group and a subsequent group having a negative refractive force including at least one lens group, and the first lens group has an optical axis at the time of scaling. The distance between the first lens group and the second lens group changes, the distance between the second lens group and the intermediate group changes, the distance between the intermediate group and the succeeding group changes, and the second The lens group has a second lens group front group fixed at the time of image blur correction in order from the object side to the image side, and a negative refractive force that moves in the direction intersecting the optical axis at the time of image blur correction. It consists of an anti-vibration group, and the difference in the optical axis direction between the position of the first lens group at the telephoto end and the position of the first lens group at the wide-angle end is DL1, and the lens on the most object side of the entire system at the wide-angle end. The distance on the optical axis from the surface to the lens surface on the image side of the entire system at the wide-angle end is Lw, the lateral magnification of the anti-vibration group at the telephoto end when focused on an infinity object is βist, and the infinity object. When the combined lateral magnification of all lenses on the image side of the anti-vibration group at the telephoto end in the focused state is βisrt.
0.4 <DL1 / Lw <1 (1)
3.5 << (1-βist) × βisrt | <7 (2)
Satisfy the conditional expressions (1) and (2) represented by.

The intermediate group consists of an intermediate group A having a positive refractive power and an intermediate group B having a positive refractive power in order from the object side to the image side. It may be configured so that the interval between the two is changed. In that case, it is preferable that only the intermediate group B moves along the optical axis during focusing.

In a configuration in which only the intermediate B group moves along the optical axis during focusing, when the focal length of the intermediate A group is fmA and the focal length of the intermediate B group is fmB,
0.5 <fmA / fmB <2 (3)
It is preferable to satisfy the conditional expression (3) represented by.

In a configuration in which only the intermediate B group moves along the optical axis during focusing, the distance between the intermediate A group and the intermediate B group at the telephoto end in the state of being in focus on an infinity object is DmAB. When the focal length of the intermediate group B is fmB,
0.3 <DmAB / fmB <1 (4)
It is preferable to satisfy the conditional expression (4) represented by.

In a configuration in which only the intermediate B group moves along the optical axis during focusing, the lateral magnification of the intermediate B group at the telephoto end in the state of focusing on the infinity object is βmbt, and the state of focusing on the infinity object. When the combined lateral magnification of all the lenses on the image side of the middle group B at the telephoto end is βmBrt,
3 << (1-βmBt ² ) × βmBrt ² | <10 (5)
It is preferable to satisfy the conditional expression (5) represented by.

When the distance on the optical axis from the lens surface on the most object side of the entire system at the telephoto end to the lens surface on the most object side of the anti-vibration group at the telephoto end is L1ist, and the focal length of the first lens group is f1. ,
0.57 <L1ist / f1 <0.7 (6)
It is preferable to satisfy the conditional expression (6) represented by.

The front group of the second lens group preferably has a positive refractive power.

When the focal length of the entire system at the wide-angle end is fw and the focal length of the anti-vibration group is fis when the object is in focus at infinity.
1 <fw / | fis | <5 (7)
It is preferable to satisfy the conditional expression (7) represented by.

When the focal length of the entire system at the wide-angle end when focused on an infinity object is fw, and the focal length of the middle group at the wide-angle end when focused on an infinity object is fmw.
1 <fw / fmw <5 (8)
It is preferable to satisfy the conditional expression (8) represented by.

When the focal length of the entire system at the telephoto end when focused on an infinity object is ft, and the focal length of the intermediate group at the telephoto end when focused on an infinity object is fmt.
5 <ft / fmt <10 (9)
It is preferable to satisfy the conditional expression (9) represented by.

When the focal length of the middle group at the telephoto end in the state of being in focus on an infinity object is fmt, and the focal length of the middle group at the wide-angle end in the state of being in focus on an infinity object is fmw.
0.8 <fmt / fmw <1.8 (10)
It is preferable to satisfy the conditional expression (10) represented by.

When the focal length of the entire system at the wide-angle end in the focused state of an infinite object is fw, and the focal length of the lens group with the strongest negative refractive power in the subsequent group is fsmax.
1 <fw / | fsmax | <4 (11)
It is preferable to satisfy the conditional expression (11) represented by.

The subsequent group consists of a lens group having a negative refractive power and a lens group having a positive refractive power in order from the object side to the image side, and the lens group having the negative refractive power at the time of scaling. It is preferable that the distance from the lens group having a positive refractive power changes.

It is preferable that the aperture is arranged between the second lens group and the intermediate group.

When the focal length of the entire system at the telephoto end in focus on an infinity object is ft, and the focal length of the entire system at the wide-angle end in focus on an infinity object is fw.
3 <ft / fw <5 (12)
It is preferable to satisfy the conditional expression (12) represented by.

The distance on the optical axis from the lens surface on the most object side of the whole system at the wide-angle end to the lens surface on the most image side of the whole system at the wide-angle end is Lw, at the wide-angle end when focused on an infinity object. When the focal length of the whole system is fw,
1.3 <Lw / fw <1.6 (13)
It is preferable to satisfy the conditional expression (13) represented by.

When the back focus of the entire system at the wide-angle end in focus on an infinity object is Bfw, and the focal length of the entire system at the wide-angle end in focus on an infinity object is fw.
0.35 <Bfw / fw <0.55 (14)
It is preferable to satisfy the conditional expression (14) represented by.

It is preferable that the succeeding group includes a lens group fixed to the image plane at the time of scaling to the image side most.

The image pickup apparatus of the present disclosure includes the zoom lens of the present disclosure.

In addition, "consisting of" and "consisting of" in the present specification refer to lenses having substantially no refractive power other than the listed components, and lenses such as an aperture, a filter, and a cover glass. It is intended that optical elements other than the above, as well as mechanical parts such as a lens flange, a lens barrel, an image pickup element, and an image stabilization mechanism, and the like may be included.

As used herein, the term "group having a positive refractive power" means that the group as a whole has a positive refractive power. Similarly, the "group having a negative refractive power" means that the group as a whole has a negative refractive power. "Lens with positive refractive power" and "positive lens" are synonymous. "Lens with negative refractive power" and "negative lens" are synonymous. The “~ lens group” is not limited to a configuration consisting of a plurality of lenses, but may be a configuration consisting of only one lens.

A compound aspherical lens (a lens in which a spherical lens and an aspherical film formed on the spherical lens are integrally formed and function as one aspherical lens as a whole) is regarded as a junction lens. Instead, treat it as a single lens. Unless otherwise specified, the sign and surface shape of the refractive power of the lens including the aspherical surface will be considered in the paraxial region.

As used herein, the term "whole system" means a zoom lens. The "back focus at the air conversion distance" is the air conversion distance on the optical axis from the lens plane on the image side of the entire system to the image plane in a state of being in focus on an infinite object. The "focal length" used in the conditional expression is the paraxial focal length. The value used in the conditional expression is a value when the d line is used as a reference in a state where the object is in focus at infinity. The "d line", "C line", "F line", and "g line" described in the present specification are emission lines. In the present specification, the wavelength of the d line is 587.56 nm (nanometers), the wavelength of the C line is 656.27 nm (nanometers), the wavelength of the F line is 486.13 nm (nanometers), and the wavelength of the g line is Treat as 435.84 nm (nanometers).

According to the present disclosure, it is possible to provide a zoom lens which has anti-vibration performance, is advantageous for miniaturization and weight reduction, and maintains good optical performance, and an image pickup apparatus provided with the zoom lens.

It is a figure which shows the cross-sectional view and the moving direction of the structure of the zoom lens of Example 1. FIG. It is sectional drawing which shows the structure and the luminous flux in each variable magnification state of the zoom lens of Example 1. FIG. It is each aberration diagram of the zoom lens of Example 1. FIG. It is a figure which shows the cross-sectional view of the structure of the zoom lens of Example 2 and the moving direction. It is each aberration diagram of the zoom lens of Example 2. FIG. It is a figure which shows the cross-sectional view and the moving direction of the structure of the zoom lens of Example 3. FIG. It is each aberration diagram of the zoom lens of Example 3. FIG. It is a figure which shows the cross-sectional view and the moving direction of the structure of the zoom lens of Example 4. FIG. It is each aberration diagram of the zoom lens of Example 4. FIG. It is a figure which shows the cross-sectional view and the moving direction of the structure of the zoom lens of Example 5. It is each aberration diagram of the zoom lens of Example 5. FIG. It is a perspective view of the front side of the image pickup apparatus which concerns on one Embodiment. It is a perspective view of the back side of the image pickup apparatus which concerns on one Embodiment.

Hereinafter, embodiments of the present disclosure will be described. The zoom lens according to the embodiment of the present disclosure has a first lens group having a positive refractive power and a negative refractive power continuously arranged in the first lens group in order from the object side to the image side. It includes a second lens group, an intermediate group having a positive refractive power including at least one lens group, and a subsequent group having a negative power including at least one lens group. When scaling from the wide-angle end to the telephoto end, the first lens group moves along the optical axis, the distance between the first lens group and the second lens group changes, and the second lens group and the intermediate group The interval between the intermediate group and the subsequent group changes. By adopting such a configuration, it is possible to realize scaling from the wide-angle end to the telephoto end, it is easy to configure it in a small size even in this scaled state, and it is possible to suppress aberration fluctuations due to scaling. Becomes easier.

The term "lens group" as used herein refers to a component of a zoom lens that includes at least one lens, which is divided by an air interval that changes during scaling. At the time of scaling, the lens group is moved or fixed in units of the lens group, and the mutual distance between the lenses in one lens group does not change.

The second lens group is a group in front of the second lens group that is fixed at the time of image blur correction in order from the object side to the image side, and a negative refractive power that moves in the direction intersecting the optical axis at the time of image blur correction. It consists of a vibration-proof group having. By making only a part of the second lens group an anti-vibration group instead of making the entire second lens group an anti-vibration group, the entire second lens group and the anti-vibration group are given different refractive powers from each other. be able to. This makes it easy to control the refractive power of the anti-vibration group, which is advantageous for ensuring good anti-vibration performance and downsizing the anti-vibration group.

The front group of the second lens group preferably has a positive refractive power. In this case, the diameter of the light flux incident on the vibration isolation group can be reduced, which is advantageous for reducing the diameter of the vibration isolation unit. Further, when the front group of the second lens group has a positive refractive power, it becomes easy to increase the negative refractive power of the anti-vibration group, so that the amount of movement of the anti-vibration group at the time of image blur correction is shortened. It becomes advantageous to.

The intermediate group consists of an intermediate group A having a positive refractive power and an intermediate group B having a positive refractive power in order from the object side to the image side. Can be configured to vary in spacing. In this case, the positive refractive power of the intermediate group can be shared between the intermediate A group and the intermediate B group, which is advantageous in suppressing the fluctuation of the spherical aberration at the time of scaling.

When the intermediate group consists of the intermediate A group and the intermediate B group, it is preferable that only the intermediate B group moves along the optical axis at the time of focusing. In the following, the group that moves during focusing will be referred to as the focus group. When the intermediate B group is set as the focus group, the focus group is located adjacent to the image side of the intermediate A group having a positive refractive power, which is advantageous for reducing the diameter of the focus group.

Next, a preferable configuration regarding the conditional expression will be described. However, the conditional expression that the zoom lens of the present disclosure is preferably satisfied with is not limited to the conditional expression described in the form of the expression, and the lower limit and the upper limit are arbitrarily selected from the preferable and more preferable conditional expressions. Includes all conditional expressions obtained in combination with. In the following description of preferred configurations and possible configurations, the zoom lens of the present disclosure is also referred to as a zoom lens.

The difference in the optical axis direction between the position of the first lens group at the telephoto end and the position of the first lens group at the wide-angle end is DL1, and the entire system at the wide-angle end from the lens surface on the most object side to the wide-angle end. When the distance on the optical axis to the lens surface on the most image side of the system is Lw, it is preferable that the zoom lens satisfies the following conditional expression (1). By preventing the corresponding value of the conditional expression (1) from becoming less than the lower limit, the amount of movement of the first lens group at the time of scaling does not become too small, which is advantageous for increasing the scaling ratio. By preventing the corresponding value of the conditional expression (1) from exceeding the upper limit, the amount of movement of the first lens group at the time of scaling does not become too large, which is advantageous for shortening the total length, and also reducing the diameter and reducing the diameter. It is advantageous for weight reduction. By satisfying the conditional expression (1), it is advantageous to obtain a high scaling ratio while being compact and lightweight. In order to obtain better characteristics, it is more preferable that the zoom lens satisfies the following conditional expression (1-1).
0.4 <DL1 / Lw <1 (1)
0.5 <DL1 / Lw <0.85 (1-1)

The lateral magnification of the anti-vibration group at the telephoto end when focused on an infinity object is βist, and the combined lateral magnification of all lenses on the image side of the anti-vibration group at the telephoto end when focused on an infinity object. When βisrt is used, the zoom lens preferably satisfies the following conditional expression (2). By preventing the corresponding value of the conditional expression (2) from becoming less than the lower limit, the amount of movement of the vibration isolation group at the time of image blur correction does not become too large, which is advantageous for miniaturization. By preventing the corresponding value of the conditional expression (2) from exceeding the upper limit, the position accuracy of the vibration isolation group at the time of image blur correction does not become too sensitive, so that control becomes easy. Satisfying the conditional expression (2) is advantageous in reducing the size of the vibration isolation unit and ensuring suitable vibration isolation performance. In order to obtain better characteristics, it is more preferable that the zoom lens satisfies the following conditional expression (2-1).
3.5 << (1-βist) × βisrt | <7 (2)
3.5 << (1-βist) × βisrt | <5.5 (2-1)

In a configuration in which the intermediate group consists of the intermediate A group and the intermediate B group and the focus group consists of the intermediate B group, when the focal length of the intermediate A group is fmA and the focal length of the intermediate B group is fmB, the zoom lens Is preferably satisfied with the following conditional expression (3). By preventing the corresponding value of the conditional expression (3) from becoming less than the lower limit, the movement amount of the focus group at the time of focusing does not become too large, which is advantageous in shortening the total length. By preventing the corresponding value of the conditional expression (3) from exceeding the upper limit, it is advantageous to suppress fluctuations in spherical aberration during focusing. Satisfying the conditional expression (3) is advantageous in shortening the total length and suppressing spherical aberration. In order to obtain better characteristics, it is more preferable that the zoom lens satisfies the following conditional expression (3-1).
0.5 <fmA / fmB <2 (3)
0.8 <fmA / fmB <1.2 (3-1)

In the configuration in which the intermediate group consists of the above intermediate A group and the intermediate B group, and the focus group consists of the intermediate B group, the light between the intermediate A group and the intermediate B group at the telephoto end in the state of being in focus on the infinity object. When the distance on the axis is DmAB and the focal length of the intermediate group B is fmB, the zoom lens preferably satisfies the following conditional expression (4). By preventing the corresponding value of the conditional expression (4) from becoming less than the lower limit, DmAB does not become too narrow as compared with the refractive power of the intermediate group B, which is advantageous for short-distance photography. By preventing the corresponding value of the conditional expression (4) from becoming less than the lower limit, DmAB does not become too wide as compared with the refractive power of the intermediate group B, which is advantageous for miniaturization. Satisfying the conditional expression (4) is advantageous for shortening the shortest shooting distance and reducing the size. In order to obtain better characteristics, it is more preferable that the zoom lens satisfies the following conditional expression (4-1).
0.3 <DmAB / fmB <1 (4)
0.35 <DmAB / fmB <0.7 (4-1)

In the configuration where the intermediate group consists of the intermediate A group and the intermediate B group and the focus group consists of the intermediate B group, the lateral magnification of the intermediate B group at the telephoto end in the state of being in focus on the infinity object is βmBt, infinite. When the combined lateral magnification of all the lenses on the image side from the intermediate group B at the telephoto end in the state of being in focus on a distant object is βmBrt, it is preferable that the zoom lens satisfies the following conditional expression (5). By preventing the corresponding value of the conditional expression (5) from becoming less than the lower limit, the amount of movement of the focus group when focusing on the short distance side does not become too large, which is advantageous for miniaturization. By preventing the corresponding value of the conditional expression (5) from exceeding the upper limit, the position accuracy of the focus group at the time of focusing does not become too sensitive, so that control becomes easy. Satisfying the conditional expression (5) is advantageous in reducing the size of the focus unit and shortening the shortest shooting distance. In order to obtain better characteristics, it is more preferable that the zoom lens satisfies the following conditional expression (5-1).
3 << (1-βmBt ² ) × βmBrt ² | <10 (5)
5 << (1-βmBt ² ) × βmBrt ² | <7 (5-1)

When the distance on the optical axis from the lens surface on the most object side of the entire system at the telephoto end to the lens surface on the most object side of the anti-vibration group at the telephoto end is L1ist, and the focal length of the first lens group is f1. The zoom lens preferably satisfies the following conditional expression (6). By preventing the corresponding value of the conditional expression (6) from becoming less than the lower limit, the refractive power of the first lens group does not become too weak, so that the diameter of the incident light flux to the vibration isolation group is reduced, especially at the telephoto end. This makes it possible to reduce the diameter of the vibration isolation unit, which is advantageous. By preventing the corresponding value of the conditional expression (6) from exceeding the upper limit, it is advantageous to shorten the total length, or it becomes easy to correct various aberrations, particularly spherical aberration, over the entire system. Satisfying the conditional expression (6) is advantageous for miniaturization and aberration correction. In order to obtain better characteristics, it is more preferable that the zoom lens satisfies the following conditional expression (6-1).
0.57 <L1ist / f1 <0.7 (6)
0.58 <L1ist / f1 <0.67 (6-1)

When the focal length of the entire system at the wide-angle end in the in-focus state of an infinity object is fw and the focal length of the anti-vibration group is fis, the zoom lens preferably satisfies the following conditional equation (7). By preventing the corresponding value of the conditional expression (7) from becoming less than the lower limit, the amount of movement of the vibration isolation group at the time of image blur correction does not become too large, which is advantageous for miniaturization. By preventing the corresponding value of the conditional expression (7) from exceeding the upper limit, the position accuracy of the vibration isolation group at the time of image blur correction does not become too sensitive, so that control becomes easy. Satisfying the conditional expression (7) is advantageous in reducing the size of the vibration isolation unit and ensuring suitable vibration isolation performance. In order to obtain better characteristics, it is more preferable that the zoom lens satisfies the following conditional expression (7-1).
1 <fw / | fis | <5 (7)
2 <fw / | fis | <4 (7-1)

When the focal length of the entire system at the wide-angle end when focused on an infinity object is fw, and the focal length of the intermediate group at the wide-angle end when focused on an infinity object is fmw, the zoom lens has the following conditions. It is preferable to satisfy the formula (8). By preventing the corresponding value of the conditional expression (8) from becoming less than the lower limit, it is possible to suppress an increase in the diameter of the light flux incident on the subsequent group, which is advantageous for the decrease in diameter. By preventing the corresponding value of the conditional expression (8) from exceeding the upper limit, it becomes easy to suppress the aberration fluctuation at the time of scaling. Satisfying the conditional expression (8) is advantageous in suppressing aberration fluctuations during diameter reduction and scaling. In order to obtain better characteristics, it is more preferable that the zoom lens satisfies the following conditional expression (8-1).
1 <fw / fmw <5 (8)
2 <fw / fmw <3.5 (8-1)

When the focal length of the entire system at the telephoto end in focus on an infinity object is ft and the focal length of the intermediate group at the telephoto end in focus on an infinity object is fmt, the zoom lens has the following conditions. It is preferable to satisfy the formula (9). By preventing the corresponding value of the conditional expression (9) from becoming less than or equal to the lower limit, it is possible to suppress an increase in the diameter of the light flux incident on the subsequent group, which is advantageous for reducing the diameter. By preventing the corresponding value of the conditional expression (9) from exceeding the upper limit, it becomes easy to suppress the aberration fluctuation at the time of scaling. Satisfying the conditional expression (9) is advantageous in suppressing aberration fluctuations during diameter reduction and scaling. In order to obtain better characteristics, it is more preferable that the zoom lens satisfies the following conditional expression (9-1).
5 <ft / fmt <10 (9)
6.5 <ft / fmt <8.5 (9-1)

When the focal length of the middle group at the wide-angle end in focus on an infinity object is fmw and the focal length of the middle group at the telephoto end in focus on an infinity object is fmt, the zoom lens has the following conditions. It is preferable to satisfy the formula (10). By preventing the corresponding value of the conditional expression (10) from becoming less than the lower limit, it is advantageous to suppress the aberration fluctuation on the telephoto side at the time of scaling. By preventing the corresponding value of the conditional expression (10) from exceeding the upper limit, it is advantageous to suppress the aberration fluctuation on the wide-angle side at the time of scaling. Satisfying the conditional expression (10) is advantageous in suppressing aberration fluctuations during scaling. In order to obtain better characteristics, it is more preferable that the zoom lens satisfies the following conditional expression (10-1).
0.8 <fmt / fmw <1.8 (10)
1.1 <fmt / fmw <1.7 (10-1)

When the focal length of the entire system at the wide-angle end in the focused state of an infinite object is fw, and the focal length of the lens group with the strongest negative refractive power in the subsequent group is fsmax, the zoom lens has the following conditional expression ( It is preferable to satisfy 11). By preventing the corresponding value of the conditional expression (11) from becoming less than or equal to the lower limit, it is advantageous for increasing the scaling ratio. By preventing the corresponding value of the conditional expression (11) from exceeding the upper limit, it is advantageous to suppress the fluctuation of aberration at the time of scaling, particularly the fluctuation of astigmatism. By satisfying the conditional expression (11), it is advantageous to increase the magnification ratio and suppress the aberration fluctuation at the time of scaling. In particular, the above effect is remarkably obtained when the lens group having the strongest negative refractive power in the subsequent group is a lens group that moves at the time of scaling. In order to obtain better characteristics, it is more preferable that the zoom lens satisfies the following conditional expression (11-1).
1 <fw / | fsmax | <4 (11)
2 <fw / | fsmax | <3.5 (11-1)

When the focal length of the entire system at the telephoto end in focus on an infinity object is ft and the focal length of the entire system at the wide-angle end in focus on an infinity object is fw, the zoom lens has the following conditions. It is preferable to satisfy the formula (12). By preventing the corresponding value of the conditional expression (12) from becoming less than the lower limit, it becomes easy to secure a magnification ratio suitable for a zoom lens. By preventing the corresponding value of the conditional expression (12) from exceeding the upper limit, it is advantageous for miniaturization. Satisfying the conditional expression (12) is advantageous in ensuring a suitable scaling ratio while being compact. In order to obtain better characteristics, it is more preferable that the zoom lens satisfies the following conditional expression (12-1).
3 <ft / fw <5 (12)
3.9 <ft / fw <4.2 (12-1)

The distance on the optical axis from the lens surface on the most object side of the whole system at the wide-angle end to the lens surface on the most image side of the whole system at the wide-angle end is Lw, at the wide-angle end when the object is in focus at infinity. When the focal length of the entire system is fw, it is preferable that the zoom lens satisfies the following conditional expression (13). By preventing the corresponding value of the conditional expression (13) from becoming less than the lower limit, it is advantageous to suppress the curvature of field. By preventing the corresponding value of the conditional expression (13) from exceeding the upper limit, it is advantageous to shorten the total length, which is also advantageous to reduce the weight. Satisfying the conditional expression (13) is advantageous in suppressing curvature of field, reducing the size, and reducing the weight. In order to obtain better characteristics, it is more preferable that the zoom lens satisfies the following conditional expression (13-1).
1.3 <Lw / fw <1.6 (13)
1.35 <Lw / fw <1.55 (13-1)

When the back focus of the entire system at the wide-angle end in focus on an infinity object is Bfw, and the focal length of the entire system at the wide-angle end in focus on an infinity object is fw. The zoom lens preferably satisfies the following conditional expression (14). By preventing the corresponding value of the conditional expression (14) from becoming less than the lower limit, it is possible to suppress an increase in the outer diameter of the lens on the image side, which is advantageous for miniaturization and weight reduction. By preventing the corresponding value of the conditional expression (14) from exceeding the upper limit, it is advantageous for correction of chromatic aberration of magnification, and it is advantageous for weight reduction because the total length can be shortened. Satisfying the conditional expression (14) is advantageous for correction of chromatic aberration of magnification, miniaturization, and weight reduction. In order to obtain better characteristics, it is more preferable that the zoom lens satisfies the following conditional expression (14-1).
0.35 <Bfw / fw <0.55 (14)
0.35 <Bfw / fw <0.48 (14-1)

When the radius of curvature of the lens surface on the most image side of the first lens group is R1r and the radius of curvature of the lens surface on the most object side of the second lens group is R2f, the zoom lens satisfies the following conditional equation (15). Is preferable. Satisfying the conditional equation (15) is advantageous in suppressing fluctuations in spherical aberration during scaling, and thereby facilitates reducing the burden of aberration correction for other lens groups. In order to obtain better characteristics, it is more preferable that the zoom lens satisfies the following conditional expression (15-1).
0.8 <(R1r + R2f) / (R1r-R2f) <4 (15)
1.2 <(R1r + R2f) / (R1r-R2f) <2.5 (15-1)

The lateral magnification of the anti-vibration group at the wide-angle end when focused on an infinity object is βisw, and the combined lateral magnification of all lenses on the image side of the anti-vibration group at the wide-angle end when focused on an infinity object. When βisrw is used, it is preferable that the zoom lens satisfies the following conditional expression (16). By preventing the corresponding value of the conditional expression (16) from becoming less than the lower limit, the amount of movement of the vibration isolation group at the time of image blur correction does not become too large, which is advantageous for miniaturization. By preventing the corresponding value of the conditional expression (16) from exceeding the upper limit, the position accuracy of the vibration isolation group at the time of image blur correction does not become too sensitive, so that control becomes easy. By satisfying the conditional expression (16), it is advantageous to reduce the size of the anti-vibration unit and secure suitable anti-vibration performance. In order to obtain better characteristics, it is more preferable that the zoom lens satisfies the following conditional expression (16-1).
1 << (1-βisw) × βisrw | <5 (16)
1.75 << (1-βisw) × βisrw | <3 (16-1)

In the configuration where the intermediate group consists of the intermediate A group and the intermediate B group and the focus group consists of the intermediate B group, the lateral magnification of the intermediate B group at the wide-angle end in the focused state of the infinity object is βmBw, infinite. When the combined lateral magnification of all the lenses on the image side from the intermediate B group at the wide-angle end in the state of being in focus on a distant object is βmBrw, it is preferable that the zoom lens satisfies the following conditional expression (17). By preventing the corresponding value of the conditional expression (17) from becoming less than the lower limit, the amount of movement of the focus group when focusing on the short distance side does not become too large, which is advantageous for miniaturization. By preventing the corresponding value of the conditional expression (17) from exceeding the upper limit, the position accuracy of the focus group at the time of focusing does not become too sensitive, so that control becomes easy. Satisfying the conditional expression (17) is advantageous in reducing the size of the focus unit and shortening the shortest shooting distance. In order to obtain better characteristics, it is more preferable that the zoom lens satisfies the following conditional expression (17-1).
1 << (1-βmbw ² ) × βmBrw ² | <10 (17)
3 << (1-βmbw ² ) × βmBrw ² | <5 (17-1)

When the focal length of the entire system at the wide-angle end in a state of being in focus on an infinity object is fw and the focal length of the first lens group is f1, the zoom lens preferably satisfies the following conditional equation (18). By preventing the corresponding value of the conditional expression (18) from becoming less than the lower limit, it is possible to suppress an increase in the diameter of the light flux incident on the second lens group, which is advantageous for miniaturization of the entire system. By preventing the corresponding value of the conditional expression (18) from exceeding the upper limit, it becomes easy to correct various aberrations, particularly spherical aberration, over the entire system. Satisfying the conditional expression (18) is advantageous for miniaturization and correction of various aberrations. In order to obtain better characteristics, it is more preferable that the zoom lens satisfies the following conditional expression (18-1).
0.3 <fw / f1 <0.8 (18)
0.4 <fw / f1 <0.7 (18-1)

When the focal length of the entire system at the telephoto end in a state of being in focus on an infinity object is ft and the focal length of the first lens group is f1, the zoom lens preferably satisfies the following conditional equation (19). By preventing the corresponding value of the conditional expression (19) from becoming less than the lower limit, it is possible to suppress an increase in the diameter of the light flux incident on the second lens group, which is advantageous for miniaturization of the entire system. By preventing the corresponding value of the conditional expression (19) from exceeding the upper limit, it becomes easy to correct various aberrations, particularly spherical aberration, over the entire system. Satisfying the conditional expression (19) is advantageous for miniaturization and correction of various aberrations. In order to obtain better characteristics, it is more preferable that the zoom lens satisfies the following conditional expression (19-1).
1.7 <ft / f1 <3 (19)
1.8 <ft / f1 <2.7 (19-1)

When the focal length of the entire system at the telephoto end in a state of being in focus on an infinity object is ft and the focal length of the second lens group is f2, the zoom lens preferably satisfies the following conditional equation (20). By preventing the corresponding value of the conditional expression (20) from becoming less than or equal to the lower limit, it is advantageous for increasing the scaling ratio. By preventing the corresponding value of the conditional expression (20) from exceeding the upper limit, it is possible to suppress an increase in the diameter of the light flux incident on the intermediate group, which is advantageous for miniaturization of the entire system. Satisfying the conditional expression (20) is advantageous for high variable ratio and miniaturization. In order to obtain better characteristics, it is more preferable that the zoom lens satisfies the following conditional expression (20-1).
7 <ft / | f2 | <15 (20)
8 <ft / | f2 | <14 (20-1)

When the focal length of the intermediate group at the wide-angle end in the in-focus state of an infinity object is fmw and the focal length of the second lens group is f2, the zoom lens preferably satisfies the following conditional expression (21). By preventing the corresponding value of the conditional expression (21) from becoming less than the lower limit, the negative refractive power of the second lens group does not become too weak, which is advantageous for high magnification ratio. By preventing the corresponding value of the conditional expression (21) from exceeding the upper limit, the negative refractive power of the second lens group does not become too strong, so that the light flux incident on the intermediate group and the group on the image side from the intermediate group It is possible to suppress the increase in diameter, which is advantageous for miniaturization. Satisfying the conditional expression (21) is advantageous for high variable ratio and miniaturization. In order to obtain better characteristics, it is more preferable that the zoom lens satisfies the following conditional expression (21-1).
0.8 <fmw / | f2 | <1.3 (21)
0.85 <fmw / | f2 | <1.1 (21-1)

When the focal length of the intermediate group at the telephoto end is fmt and the focal length of the second lens group is f2 in a state of being in focus on an infinity object, the zoom lens preferably satisfies the following conditional expression (22). By preventing the corresponding value of the conditional expression (22) from becoming less than the lower limit, the negative refractive power of the second lens group does not become too weak, which is advantageous for high magnification ratio. By preventing the corresponding value of the conditional expression (22) from exceeding the upper limit, the negative refractive power of the second lens group does not become too strong, so that the light flux incident on the image side group from the intermediate group and the intermediate group It is possible to suppress the increase in diameter, which is advantageous for miniaturization. Satisfying the conditional expression (22) is advantageous for high variable ratio and miniaturization. In order to obtain better characteristics, it is more preferable that the zoom lens satisfies the following conditional expression (22-1).
0.9 <fmt / | f2 | <2 (22)
1 <fmt / | f2 | <1.8 (22-1)

The intermediate group includes at least one positive lens, and when the Abbe number of the positive lens of the intermediate group is νmp, the intermediate group contains at least one positive lens satisfying the following conditional expression (23). Is preferable. By preventing the corresponding value of the conditional expression (23) from becoming less than the lower limit, it is advantageous for correcting the axial chromatic aberration on the telephoto side. By preventing the corresponding value of the conditional expression (23) from exceeding the upper limit, it is possible to prevent the refractive index of the positive lens from becoming too low. This makes it easy to secure the refractive power without making the absolute value of the radius of curvature of the lens surface extremely small, and it is possible to prevent the lens from expanding in the optical axis direction. It is advantageous for the conversion. Satisfying the conditional expression (23) is advantageous in correcting axial chromatic aberration, reducing the size, and reducing the weight. In order to obtain better characteristics, it is more preferable that the intermediate group contains at least one positive lens satisfying the following conditional expression (23-1).
70 <νmp <100 (23)
80 <νmp <96 (23-1)

In a configuration in which the front group of the second lens group has a positive refractive power, when the Abbe number of the positive lens of the front group of the second lens group is ν2p, the front group of the second lens group has the following conditional expression (24). ) Satisfying at least one positive lens. By preventing the corresponding value of the conditional expression (24) from becoming less than the lower limit, it is advantageous for correcting the axial chromatic aberration on the telephoto side. By preventing the corresponding value of the conditional expression (24) from becoming more than the upper limit, it is possible to prevent the refractive index of the positive lens from becoming too low. This makes it easy to secure the refractive power without making the absolute value of the radius of curvature of the lens surface extremely small, and it is possible to prevent the lens from becoming enlarged in the optical axis direction. It is advantageous for miniaturization and weight reduction. Satisfying the conditional expression (24) is advantageous in correcting axial chromatic aberration, reducing the size, and reducing the weight. In order to obtain better characteristics, it is more preferable that the front group of the second lens group contains at least one positive lens satisfying the following conditional expression (24-1).
50 <ν2p <90 (24)
65 <ν2p <85 (24-1)

When the radius of curvature of the lens surface on the most object side of the first lens group is R1f and the radius of curvature of the lens surface on the most image side of the first lens group is R1r, the zoom lens satisfies the following conditional equation (25). Is preferable. Satisfying the conditional expression (25) is advantageous for correcting spherical aberration, and thereby makes it easy to reduce the burden of correcting aberrations of other lens groups. In order to obtain better characteristics, it is more preferable that the zoom lens satisfies the following conditional expression (25-1).
-6 <(R1f + R1r) / (R1f-R1r) <-1 (25)
-5 <(R1f + R1r) / (R1f-R1r) <-2 (25-1)

When the average value of the Abbe numbers on the d-line reference of all the positive lenses in the first lens group is νave1p, it is preferable that the zoom lens satisfies the following conditional expression (26). By preventing the corresponding value of the conditional expression (26) from becoming less than the lower limit, it is advantageous for correcting the axial chromatic aberration on the telephoto side. By preventing the corresponding value of the conditional expression (26) from exceeding the upper limit, it is possible to prevent the refractive index of the positive lens from becoming too low. This makes it easy to secure the refractive power without making the absolute value of the radius of curvature of the lens surface extremely small, and it is possible to prevent the lens from becoming enlarged in the optical axis direction. Therefore, the size of the first lens group is reduced. And it is advantageous for weight reduction. Satisfying the conditional expression (26) is advantageous in correcting axial chromatic aberration, reducing the size, and reducing the weight. In order to obtain better characteristics, it is more preferable that the zoom lens satisfies the following conditional expression (26-1).
65 <νave1p <85 (26)
70 <νave1p <80 (26-1)

When the average value of the Abbe numbers on the d-line reference of all the negative lenses in the second lens group is νave2n, the zoom lens preferably satisfies the following conditional expression (27). By preventing the corresponding value of the conditional expression (27) from becoming less than the lower limit, it is advantageous for correcting chromatic aberration. By preventing the corresponding value of the conditional expression (27) from exceeding the upper limit, it is possible to prevent the refractive index of the negative lens from becoming too low. This makes it easy to secure the refractive power without making the absolute value of the radius of curvature of the lens surface extremely small, and it is possible to prevent the volume of the lens from increasing, which is advantageous for reducing the weight of the vibration isolation unit. .. Satisfying the conditional expression (27) is advantageous for correction of chromatic aberration and weight reduction. In order to obtain better characteristics, it is more preferable that the zoom lens satisfies the following conditional expression (27-1).
30 <νave2n <60 (27)
35 <νave2n <52 (27-1)

In the configuration in which the intermediate group consists of the intermediate A group and the intermediate B group, when the average value of the Abbe numbers of all the positive lenses in the intermediate A group based on the d-line is νavemAp, the zoom lens has the following conditional expression (28). ) Satisfying. By preventing the corresponding value of the conditional expression (28) from becoming less than the lower limit, it is advantageous for correcting the axial chromatic aberration on the telephoto side. By preventing the corresponding value of the conditional expression (28) from becoming more than the upper limit, it is possible to prevent the refractive index of the positive lens from becoming too low. This makes it easy to secure the refractive power without making the absolute value of the radius of curvature of the lens surface extremely small, and it is possible to prevent the lens from expanding in the optical axis direction. It is advantageous for the conversion. Satisfying the conditional expression (28) is advantageous in correcting axial chromatic aberration, reducing the size, and reducing the weight. In order to obtain better characteristics, it is more preferable that the zoom lens satisfies the following conditional expression (28-1).
60 <νavemAp <85 (28)
67 <νavemAp <80 (28-1)

The anti-vibration group includes at least one positive lens, and when the Abbe number of the d-line reference of the positive lens of the anti-vibration group is νisp, the anti-vibration group includes at least one positive lens satisfying the following conditional expression (29). It is preferable to include one sheet. Satisfying the conditional expression (29) is advantageous in suppressing fluctuations in chromatic aberration of magnification during image blur correction. In order to obtain better characteristics, it is more preferable that the vibration isolation group includes at least one positive lens satisfying the following conditional expression (29-1).
15 <νisp <40 (29)
20 <νisp <33 (29-1)

When the focal length of the entire system at the wide-angle end in a state of being in focus on an infinity object is fw and the focal length of the second lens group is f2, it is preferable that the zoom lens satisfies the following conditional expression (30). By preventing the corresponding value of the conditional expression (30) from becoming less than the lower limit, the negative refractive power of the second lens group does not become too weak, which is advantageous for high magnification ratio. By preventing the corresponding value of the conditional expression (30) from exceeding the upper limit, the negative refractive power of the second lens group does not become too strong, so that the light flux incident on the image side group from the intermediate group and the intermediate group It is possible to suppress the increase in diameter, which is advantageous for miniaturization. Satisfying the conditional expression (30) is advantageous for high variable ratio and miniaturization. In order to obtain better characteristics, it is more preferable that the zoom lens satisfies the following conditional expression (30-1).
1 <fw / | f2 | <5 (30)
2 <fw / | f2 | <3.5 (30-1)

Specifically, each group can adopt, for example, the following configuration.

The first lens group may be configured to include one negative lens and two positive lenses. In this case, it is advantageous for correcting axial chromatic aberration, and it is advantageous for weight reduction as compared with the case where the first lens group consists of four or more lenses.

For example, the first lens group may be configured to include a bonded lens in which one negative lens and one positive lens are bonded and one positive lens in order from the object side to the image side. can. More specifically, the first lens group is composed of a negative meniscus lens having a convex surface facing the object side, a biconvex lens, and a positive meniscus lens having a convex surface facing the object side in order from the object side to the image side. can do.

The number of lenses constituting the front group of the second lens group is preferably 3 or less. In this case, it is advantageous to reduce the size and weight of the entire system.

The front group of the second lens group may be configured to consist of only one positive lens, or may be configured to consist of a bonded lens in which one positive lens and one negative lens are bonded. You may.

The anti-vibration group preferably consists of two negative lenses and one positive lens. In this case, it is advantageous to suppress the performance deterioration caused by the fluctuation of chromatic aberration at the time of image blur correction. Further, when the anti-vibration group consists of two negative lenses and one positive lens, it is easier to correct chromatic aberration than when the anti-vibration group consists of two or less lenses, and the anti-vibration group has four lenses. It is advantageous in reducing the size and weight of the anti-vibration unit as compared with the case where it consists of more than one lens.

The vibration isolation group preferably includes a bonded lens in which a negative lens and a positive lens are bonded in order from the object side, or a bonded lens in which a positive lens and a negative lens are bonded in order from the object side. In this case, it is advantageous to reduce the deterioration of the optical performance due to the assembly error.

For example, the vibration isolation group can be configured to include a bonded lens in which one negative lens and one positive lens are bonded in order from the object side to the image side, and one negative lens. .. More specifically, the anti-vibration group consists of a bonded lens in which a negative lens with a concave surface facing the image side and a positive meniscus lens with a convex surface facing the object side are joined in order from the object side to the image side, and a concave surface on the object side. It can be configured to consist of a negative lens facing.

It is preferable that an aperture diaphragm is arranged between the second lens group and the intermediate group. In this case, the vibration-proof group and the aperture stop are close to each other, which is advantageous for reducing the diameter of the vibration-proof group.

The intermediate group preferably consists of two or less lens groups. In this case, it is advantageous for miniaturization and weight reduction. For example, the intermediate A group may be configured to be composed of one lens group, and the intermediate B group may be configured to be composed of one lens group.

Subsequent groups may be configured to consist of two lens groups whose mutual spacing changes upon scaling. For example, the subsequent group consists of a lens group having a negative refractive power and a lens group having a positive refractive power in order from the object side to the image side, and has the above-mentioned negative refractive power at the time of scaling. The distance between the lens group and the lens group having a positive refractive power may be changed. In this case, the lens group having a negative refractive power bounces the light ray in the direction away from the optical axis Z, and the lens group having a positive refractive power makes the angle between the light ray and the optical axis Z smaller. Therefore, it is advantageous to reduce the incident angle of the main ray of the off-axis light beam incident on the image plane while securing a large image circle.

The lens group having the largest absolute value of refractive power in the subsequent group preferably includes at least one positive lens and at least one negative lens. In this case, it is advantageous for correcting astigmatism and chromatic aberration of magnification, and it is also advantageous for suppressing aberration fluctuation at the time of scaling.

The zoom lens may be configured so that all the lens groups move at the time of scaling, or may be configured to include a lens group fixed to the image plane at the time of scaling. For example, the subsequent group may be configured to include a lens group fixed to the image plane at the time of scaling to the image side most. In this case, the lens group fixed at the time of the magnification on the image side can obtain the effect of suppressing the fluctuation of the chromatic aberration of magnification at the time of the magnification. Further, the second lens group may be configured to be fixed to the image plane at the time of scaling. In this case, it is advantageous to reduce the deterioration of the optical performance due to the error, and it is advantageous to reduce the size and weight of the device because the device can be further simplified.

The above-mentioned preferable configuration and possible configuration including the configuration related to the conditional expression can be any combination, and it is preferable that they are appropriately and selectively adopted according to the required specifications.

As an example, a preferred embodiment of the zoom lens of the present disclosure is a first lens group having a positive refractive force and a negative refractive force continuously arranged in the first lens group in order from the object side to the image side. A second lens group comprising, an intermediate group having a positive refractive force including at least one lens group, and a subsequent group having a negative refractive force including at least one lens group, and upon scaling, The first lens group moves along the optical axis, the distance between the first lens group and the second lens group changes, the distance between the second lens group and the intermediate group changes, and the distance between the intermediate group and the succeeding group changes. The interval changes, and the second lens group moves from the object side to the image side in the direction that intersects the optical axis with the front group of the second lens group, which is fixed during image blur correction. It is a zoom lens that is composed of a vibration-proof group having a negative refractive force and satisfies the above-mentioned conditional equations (1) and (2). According to this preferred embodiment of the zoom lens, it has anti-vibration performance, is advantageous for miniaturization and weight reduction, and it is easy to maintain good optical performance.

Next, an embodiment of the zoom lens of the present disclosure will be described with reference to the drawings.
[Example 1]
FIG. 1 shows a cross-sectional view of the configuration of the zoom lens of the first embodiment of the present disclosure at the wide-angle end. FIG. 2 shows a configuration of the zoom lens in each variable magnification state and a cross-sectional view of the luminous flux. In FIGS. 1 and 2, the state of focusing on an infinity object is shown, the left side is the object side, and the right side is the image side. In FIG. 2, the upper row labeled "WIDE" shows the wide-angle end state, the middle row labeled "MIDDLE" shows the intermediate focal length state, and the lower row labeled "TELE" shows the telephoto end state. In FIG. 2, as the luminous flux, the axial luminous flux wa and the maximum angle of view light flux wb in the wide angle end state, the axial luminous flux ma and the maximum angle of view luminous flux mb in the intermediate focal distance state, and the axial luminous flux ta and the maximum in the telephoto end state. The luminous flux tb of the angle of view is shown. FIG. 2 shows, as an example, Lw, DL1, and L1ist used in the above conditional expression.

The zoom lens of the first embodiment has a first lens group G1, a second lens group G2, an aperture diaphragm, a third lens group G3, and a fourth lens in order from the object side to the image side along the optical axis Z. It consists of a group G4, a fifth lens group G5, and a sixth lens group G6. In this zoom lens, when scaling from the wide-angle end to the telephoto end, the five lens groups from the first lens group G1 to the fifth lens group G5 change the distance in the optical axis direction of the adjacent lens groups. It moves along the optical axis Z, the sixth lens group G6 is fixed to the image plane Sim, and the aperture stop St moves integrally with the third lens group G3. Below each lens group in FIG. 1, for the lens group that moves during scaling, the approximate moving direction when scaling from the wide-angle end to the telephoto end is indicated by a single arrow, and when scaling is performed. A ground symbol is shown for fixed lens groups. In the zoom lens of Example 1, the intermediate group is composed of the third lens group G3 and the fourth lens group G4, and the subsequent group is composed of the fifth lens group G5 and the sixth lens group G6.

The first lens group G1 is composed of three lenses L11 to L13 in order from the object side to the image side. The second lens group G2 is composed of four lenses L21 to L24 in order from the object side to the image side. The third lens group G3 is composed of three lenses L31 to L33 in order from the object side to the image side. The fourth lens group G4 is composed of three lenses L41 to L43 in order from the object side to the image side. The fifth lens group G5 is composed of two lenses L51 to L52 in order from the object side to the image side. The sixth lens group G6 is composed of one lens of the lens L61. The anti-vibration group consists of three lenses, lenses L22 to L24. The focus group consists of a fourth lens group G4. In FIG. 1, a vertical double-headed arrow is written below the anti-vibration group, and a horizontal double-headed arrow is written below the focus group.

Note that FIGS. 1 and 2 show an example in which a parallel flat plate-shaped optical member PP is arranged between the zoom lens and the image plane Sim on the assumption that the zoom lens is applied to the image pickup apparatus. .. The optical member PP is a member that assumes various filters and / or a cover glass and the like. The various filters are, for example, a low-pass filter, an infrared cut filter, a filter that cuts a specific wavelength range, and the like. The optical member PP is a member having no refractive power, and a configuration in which the optical member PP is omitted is also possible.

For the zoom lens of Example 1, the basic lens data is shown in Table 1, the specifications and variable surface spacing are shown in Table 2, and the aspherical coefficient is shown in Table 3. In Table 1, the Sn column shows the surface number when the surface on the object side is the first surface and the number is increased by one toward the image side, and the R column shows the radius of curvature of each surface. In the column D, the surface distance between each surface and the surface adjacent to the image side on the optical axis is shown, in the column Nd, the refractive index of each component with respect to the d line is shown, and in the column νd. The Abbe number based on the d-line of each component is shown.

In Table 1, the sign of the radius of curvature of the surface having the convex surface facing the object side is positive, and the sign of the radius of curvature of the surface having the convex surface facing the image side is negative. Table 1 also shows the aperture stop St and the optical member PP. The surface number and the phrase (St) are described in the surface number column of the surface corresponding to the aperture stop St. The value in the bottom column of D in Table 1 is the distance between the surface on the image side and the image surface Sim in the table. In Table 1, the symbol DD [] is used for the variable surface spacing at the time of scaling, and the surface number on the object side of this spacing is added in [] and entered in the column D.

Table 2 shows the zoom magnification Zr, the focal length f, and the open F number FNo. , The maximum total angle of view 2ω, and the variable surface spacing at the time of scaling are shown. (°) in the column of 2ω means that the unit is degrees. In Table 2, each value of the wide-angle end state, the intermediate focal length state, and the telephoto end state is shown in the columns described as WIDE, MIDDLE, and TELE, respectively. The values shown in Tables 1 and 2 are values when the d-line is used as a reference when the object is in focus at infinity.

In Table 1, the surface numbers of the aspherical surface are marked with *, and the numerical value of the radius of curvature of the near axis is described in the column of the radius of curvature of the aspherical surface. In Table 3, the Sn column shows the surface number of the aspherical surface, and the columns KA and Am (m = 3, 4, 5, ... 10) show the numerical value of the aspherical surface coefficient for each aspherical surface. .. “E ± n” (n: integer) of the numerical value of the aspherical coefficient in Table 3 means “× 10 ^{± n} ”. KA and Am are aspherical coefficients in the aspherical expression expressed by the following equation.
Zd = C × h ² / {1 + (1-KA × C ² × h ² ) ^1/2 } + ΣAm × h ^m
However,
Zd: Aspherical depth (length of a perpendicular line drawn from a point on the aspherical surface at height h to a plane perpendicular to the optical axis where the aspherical apex touches)
h: Height (distance from the optical axis to the lens surface)
C: The reciprocal of the radius of curvature of the near axis KA, Am: the aspherical coefficient, and the aspherical Σ means the sum with respect to m.

In the data in each table, degrees are used as the unit of angle and mm (millimeter) is used as the unit of length. Units can also be used. In addition, in each table shown below, numerical values rounded with predetermined digits are listed.

FIG. 3 shows each aberration diagram in a state where the zoom lens of the first embodiment is in focus on an infinity object. In FIG. 3, spherical aberration, astigmatism, distortion, and chromatic aberration of magnification are shown in order from the left. In FIG. 3, the upper row labeled "WIDE" shows the aberration in the wide-angle end state, the middle row labeled "MIDDLE" shows the aberration in the intermediate focal length state, and the lower row labeled "TELE" shows the aberration in the telephoto end state. show. In the spherical aberration diagram, the aberrations on the d-line, C-line, F-line, and g-line are shown by solid lines, long dashed lines, short dashed lines, and alternate long and short dash lines, respectively. In the astigmatism diagram, the aberration on the d-line in the sagittal direction is shown by a solid line, and the aberration on the d-line in the tangential direction is shown by a short dashed line. In the distortion diagram, the aberration on the d line is shown by a solid line. In the chromatic aberration of magnification diagram, the aberrations in the C line, the F line, and the g line are shown by long broken lines, short broken lines, and alternate long and short dash lines, respectively. FNo. Of the spherical aberration diagram. Means F number, and ω in other aberration diagrams means a half angle of view. In FIG. 3, the FNo. And the value of ω are shown.

Unless otherwise specified, the symbols, meanings, description methods, and illustration methods of the respective data relating to the above-mentioned Example 1 are the same in the following Examples, and thus duplicate description will be omitted below.

[Example 2]
FIG. 4 shows a cross-sectional view of the configuration at the wide-angle end of the zoom lens of the second embodiment in a state of being in focus on an infinite object. The zoom lens of the second embodiment has a first lens group G1, a second lens group G2, an aperture diaphragm, a third lens group G3, and a fourth lens in order from the object side to the image side along the optical axis Z. It consists of a group G4, a fifth lens group G5, and a sixth lens group G6. In this zoom lens, when scaling from the wide-angle end to the telephoto end, the five lens groups from the first lens group G1 to the fifth lens group G5 change the distance in the optical axis direction of the adjacent lens groups. It moves along the optical axis Z, the sixth lens group G6 is fixed to the image plane Sim, and the aperture stop St moves integrally with the third lens group G3. In the zoom lens of Example 2, the intermediate group is composed of the third lens group G3 and the fourth lens group G4, and the subsequent group is composed of the fifth lens group G5 and the sixth lens group G6.

The first lens group G1 is composed of three lenses L11 to L13 in order from the object side to the image side. The second lens group G2 is composed of four lenses L21 to L24 in order from the object side to the image side. The third lens group G3 is composed of three lenses L31 to L33 in order from the object side to the image side. The fourth lens group G4 is composed of three lenses L41 to L43 in order from the object side to the image side. The fifth lens group G5 is composed of three lenses L51 to L53 in order from the object side to the image side. The sixth lens group G6 is composed of one lens of the lens L61. The anti-vibration group consists of three lenses, lenses L22 to L24. The focus group consists of a fourth lens group G4.

For the zoom lens of Example 2, the basic lens data is shown in Table 4, the specifications and variable surface spacing are shown in Table 5, the aspherical coefficient is shown in Table 6, and each aberration diagram is shown in FIG.

[Example 3]
FIG. 6 shows a cross-sectional view of the configuration at the wide-angle end of the zoom lens of Example 3 in a state of being in focus on an infinite object. The zoom lens of Example 3 has a first lens group G1, a second lens group G2, an aperture diaphragm, a third lens group G3, and a fourth lens in order from the object side to the image side along the optical axis Z. It consists of a group G4, a fifth lens group G5, and a sixth lens group G6. In this zoom lens, when scaling from the wide-angle end to the telephoto end, the five lens groups from the first lens group G1 to the fifth lens group G5 change the distance in the optical axis direction of the adjacent lens groups. It moves along the optical axis Z, the sixth lens group G6 is fixed to the image plane Sim, and the aperture stop St moves integrally with the third lens group G3. In the zoom lens of Example 3, the intermediate group is composed of the third lens group G3 and the fourth lens group G4, and the subsequent group is composed of the fifth lens group G5 and the sixth lens group G6.

The first lens group G1 is composed of three lenses L11 to L13 in order from the object side to the image side. The second lens group G2 is composed of five lenses L21 to L25 in order from the object side to the image side. The third lens group G3 is composed of three lenses L31 to L33 in order from the object side to the image side. The fourth lens group G4 is composed of two lenses L41 to L42 in order from the object side to the image side. The fifth lens group G5 is composed of two lenses L51 to L52 in order from the object side to the image side. The sixth lens group G6 is composed of one lens of the lens L61. The anti-vibration group consists of three lenses, lenses L23 to L25. The focus group consists of a fourth lens group G4.

For the zoom lens of Example 3, the basic lens data is shown in Table 7, the specifications and variable surface spacing are shown in Table 8, the aspherical coefficient is shown in Table 9, and each aberration diagram is shown in FIG.

[Example 4]
FIG. 8 shows a cross-sectional view of the configuration at the wide-angle end of the zoom lens of Example 4 in a state of being in focus on an infinite object. The zoom lens of the fourth embodiment has a first lens group G1, a second lens group G2, an aperture diaphragm, a third lens group G3, and a fourth lens in order from the object side to the image side along the optical axis Z. It consists of a group G4, a fifth lens group G5, and a sixth lens group G6. In this zoom lens, four lens groups of a first lens group G1, a third lens group G3, a fourth lens group G4, and a fifth lens group G5 are used when scaling from the wide-angle end to the telephoto end. Moves along the optical axis Z by changing the distance between adjacent lens groups in the optical axis direction, and the second lens group G2 and the sixth lens group G6 are fixed to the image plane Sim, and the aperture aperture is reduced. St moves integrally with the third lens group G3. In the zoom lens of Example 4, the intermediate group is composed of the third lens group G3 and the fourth lens group G4, and the subsequent group is composed of the fifth lens group G5 and the sixth lens group G6.

The first lens group G1 is composed of three lenses L11 to L13 in order from the object side to the image side. The second lens group G2 is composed of four lenses L21 to L24 in order from the object side to the image side. The third lens group G3 is composed of three lenses L31 to L33 in order from the object side to the image side. The fourth lens group G4 is composed of three lenses L41 to L43 in order from the object side to the image side. The fifth lens group G5 is composed of three lenses L51 to L53 in order from the object side to the image side. The sixth lens group G6 is composed of one lens of the lens L61. The anti-vibration group consists of three lenses, lenses L22 to L24. The focus group consists of a fourth lens group G4.

For the zoom lens of Example 4, the basic lens data is shown in Table 10, the specifications and variable surface spacing are shown in Table 11, the aspherical coefficient is shown in Table 12, and each aberration diagram is shown in FIG.

[Example 5]
FIG. 10 shows a cross-sectional view of the configuration at the wide-angle end of the zoom lens of Example 5 in a state of being in focus on an infinite object. The zoom lens of Example 5 has a first lens group G1, a second lens group G2, an aperture diaphragm, a third lens group G3, and a fourth lens in order from the object side to the image side along the optical axis Z. It consists of a group G4, a fifth lens group G5, and a sixth lens group G6. In this zoom lens, when scaling from the wide-angle end to the telephoto end, the five lens groups from the first lens group G1 to the fifth lens group G5 change the distance in the optical axis direction of the adjacent lens groups. It moves along the optical axis Z, the sixth lens group G6 is fixed to the image plane Sim, and the aperture stop St moves integrally with the third lens group G3. In the zoom lens of Example 5, the intermediate group is composed of the third lens group G3 and the fourth lens group G4, and the subsequent group is composed of the fifth lens group G5 and the sixth lens group G6.

The first lens group G1 is composed of three lenses L11 to L13 in order from the object side to the image side. The second lens group G2 is composed of four lenses L21 to L24 in order from the object side to the image side. The third lens group G3 is composed of three lenses L31 to L33 in order from the object side to the image side. The fourth lens group G4 is composed of three lenses L41 to L43 in order from the object side to the image side. The fifth lens group G5 is composed of two lenses L51 to L52 in order from the object side to the image side. The sixth lens group G6 is composed of one lens of the lens L61. The anti-vibration group consists of three lenses, lenses L22 to L24. The focus group consists of a fourth lens group G4.

For the zoom lens of Example 5, the basic lens data is shown in Table 13, the specifications and variable surface spacing are shown in Table 14, the aspherical coefficient is shown in Table 15, and each aberration diagram is shown in FIG.

Table 16 shows the corresponding values of the conditional expressions (1) to (30) of the zoom lenses of Examples 1 to 5.

As can be seen from the above data, the zoom lenses of Examples 1 to 5 have anti-vibration performance, and are configured to be smaller and lighter while having a zoom magnification of 4 times or more. Moreover, various aberrations are satisfactorily corrected to realize high optical performance. Further, the zoom lenses of Examples 1 to 5 are suitable as, for example, a telephoto zoom lens.

Next, the image pickup apparatus according to the embodiment of the present disclosure will be described. 12 and 13 show external views of the camera 30, which is an image pickup apparatus according to an embodiment of the present disclosure. FIG. 12 shows a perspective view of the camera 30 as viewed from the front side, and FIG. 13 shows a perspective view of the camera 30 as viewed from the rear side. The camera 30 is a so-called mirrorless type digital camera, and the interchangeable lens 20 can be detachably attached. The interchangeable lens 20 includes a zoom lens 1 according to an embodiment of the present disclosure, which is housed in a lens barrel.

The camera 30 includes a camera body 31, and a shutter button 32 and a power button 33 are provided on the upper surface of the camera body 31. Further, on the back surface of the camera body 31, an operation unit 34, an operation unit 35, and a display unit 36 are provided. The display unit 36 can display the captured image and the image within the angle of view before being captured.

A shooting opening for incident light from a shooting target is provided in the central portion of the front surface of the camera body 31, a mount 37 is provided at a position corresponding to the shooting opening, and the interchangeable lens 20 is connected to the camera body 31 via the mount 37. It is attached to.

Inside the camera body 31, an image pickup device such as a CCD (Charge Coupled Device) or CMOS (Complementary Metal Oxide Sensor) that outputs an image pickup signal corresponding to a subject image formed by the interchangeable lens 20 and an image pickup element thereof are output. A signal processing circuit that processes an image pickup signal to generate an image, a recording medium for recording the generated image, and the like are provided. The camera 30 can shoot a still image or a moving image by pressing the shutter button 32, and the image data obtained by this shooting is recorded on the recording medium.

Although the techniques of the present disclosure have been described above with reference to embodiments and examples, the techniques of the present disclosure are not limited to the above embodiments and examples, and various modifications are possible. For example, the radius of curvature, the interplanar spacing, the refractive index, the Abbe number, the aspherical coefficient, and the like of each lens are not limited to the values shown in the above embodiments, and may take other values.

Further, the image pickup apparatus according to the embodiment of the present disclosure is not limited to the above example, and may have various embodiments such as a camera other than the mirrorless type, a film camera, and a video camera.

1 Zoom lens 20 Interchangeable lens 30 Camera body 32 Shutter button 33 Power button 34, 35 Operation unit 36 Display unit 37 Mount DL1 Position of the first lens group at the telephoto end and position of the first lens group at the wide-angle end G1 1st lens group G2 2nd lens group G3 3rd lens group G4 4th lens group G5 5th lens group G6 6th lens group L11-1 to L61 Lens L1ist The most object of the whole system at the telephoto end Distance on the optical axis from the lens surface on the side to the lens surface on the most object side of the anti-vibration group at the telephoto end Lw The most image of the entire system from the lens surface on the object side at the wide-angle end to the wide-angle end Distance on the optical axis to the lens surface on the side ma, ta, wa On-axis light beam mb, tb, wb Light beam with maximum angle of view PP Optical member Sim Image plane St Aperture aperture Z Optical axis

Claims (20)

From the object side to the image side, a first lens group having a positive refractive power, a second lens group having a negative refractive power continuously arranged in the first lens group, and at least one lens group. It comprises an intermediate group having a positive power of refraction including, and a subsequent group having a negative power of refraction including at least one lens group.
At the time of scaling, the first lens group moves along the optical axis, the distance between the first lens group and the second lens group changes, and the distance between the second lens group and the intermediate group. Changes, and the distance between the intermediate group and the subsequent group changes.
The second lens group is, in order from the object side to the image side, a group in front of the second lens group fixed at the time of image blur correction and a negative refraction that moves in a direction intersecting the optical axis at the time of image blur correction. It consists of an anti-vibration group with power.
The difference in the optical axis direction between the position of the first lens group at the telephoto end and the position of the first lens group at the wide-angle end is DL1.
The distance on the optical axis from the lens surface on the most object side of the whole system at the wide-angle end to the lens surface on the image side of the whole system at the wide-angle end is Lw.
The lateral magnification of the anti-vibration group at the telephoto end when focused on an infinity object is βist.
When the combined lateral magnification of all lenses on the image side of the anti-vibration group at the telephoto end in the state of being in focus on an infinity object is βisrt.
0.4 <DL1 / Lw <1 (1)
3.5 << (1-βist) × βisrt | <7 (2)
A zoom lens that satisfies the conditional expressions (1) and (2) represented by. The intermediate group is composed of an intermediate group A having a positive refractive power and an intermediate group B having a positive refractive power in order from the object side to the image side.
The zoom lens according to claim 1, wherein the distance between the intermediate A group and the intermediate B group changes at the time of scaling. The zoom lens according to claim 2, wherein only the intermediate group B moves along the optical axis during focusing. The focal length of the intermediate group A is fmA,
When the focal length of the intermediate B group is fmB,
0.5 <fmA / fmB <2 (3)
The zoom lens according to claim 3, which satisfies the conditional expression (3) represented by. The distance on the optical axis between the intermediate A group and the intermediate B group at the telephoto end in the state of being in focus on an infinity object is DmAB.
When the focal length of the intermediate B group is fmB,
0.3 <DmAB / fmB <1 (4)
The zoom lens according to claim 3 or 4, which satisfies the conditional expression (4) represented by. The lateral magnification of the intermediate B group at the telephoto end in the state of being in focus on an infinity object is βmbt.
When the combined lateral magnification of all lenses on the image side of the intermediate B group at the telephoto end in the state of being in focus on an infinity object is βmBrt.
3 << (1-βmBt ² ) × βmBrt ² | <10 (5)
The zoom lens according to any one of claims 3 to 5, which satisfies the conditional expression (5) represented by. The distance on the optical axis from the lens surface on the most object side of the entire system at the telephoto end to the lens surface on the most object side of the vibration isolation group at the telephoto end is L1ist.
When the focal length of the first lens group is f1,
0.57 <L1ist / f1 <0.7 (6)
The zoom lens according to any one of claims 1 to 6, which satisfies the conditional expression (6) represented by. The zoom lens according to any one of claims 1 to 7, wherein the front group of the second lens group has a positive refractive power. The focal length of the entire system at the wide-angle end when focused on an object at infinity is fw,
When the focal length of the anti-vibration group is fis,
1 <fw / | fis | <5 (7)
The zoom lens according to any one of claims 1 to 8, which satisfies the conditional expression (7) represented by. The focal length of the entire system at the wide-angle end when focused on an object at infinity is fw,
When the focal length of the intermediate group at the wide-angle end in the state of being in focus on an infinity object is fmw,
1 <fw / fmw <5 (8)
The zoom lens according to any one of claims 1 to 9, which satisfies the conditional expression (8) represented by. The focal length of the entire system at the telephoto end when focused on an infinite object is ft,
When the focal length of the intermediate group at the telephoto end in the state of being in focus on an infinity object is fmt.
5 <ft / fmt <10 (9)
The zoom lens according to any one of claims 1 to 10, which satisfies the conditional expression (9) represented by. The focal length of the intermediate group at the telephoto end in the state of being in focus on an infinity object is set to fmt.
When the focal length of the intermediate group at the wide-angle end in the state of being in focus on an infinity object is fmw,
0.8 <fmt / fmw <1.8 (10)
The zoom lens according to any one of claims 1 to 11, which satisfies the conditional expression (10) represented by. The focal length of the entire system at the wide-angle end when focused on an object at infinity is fw,
When the focal length of the lens group having the strongest negative refractive power in the subsequent group is fsmax,
1 <fw / | fsmax | <4 (11)
The zoom lens according to any one of claims 1 to 12, which satisfies the conditional expression (11) represented by. The subsequent group consists of a lens group having a negative refractive power and a lens group having a positive refractive power in order from the object side to the image side.
The zoom lens according to any one of claims 1 to 13, wherein the distance between the lens group having a negative refractive power and the lens group having a positive refractive power changes at the time of scaling. The zoom lens according to any one of claims 1 to 14, wherein a diaphragm is arranged between the second lens group and the intermediate group. The focal length of the entire system at the telephoto end when focused on an infinite object is ft,
When the focal length of the entire system at the wide-angle end in the state of being in focus on an infinite object is fw,
3 <ft / fw <5 (12)
The zoom lens according to any one of claims 1 to 15, which satisfies the conditional expression (12) represented by. When the focal length of the entire system at the wide-angle end in the state of being in focus on an infinite object is fw,
1.3 <Lw / fw <1.6 (13)
The zoom lens according to any one of claims 1 to 16, which satisfies the conditional expression (13) represented by. Bfw, the back focus of the entire system at the air equivalent distance at the wide-angle end when the object is in focus at infinity,
When the focal length of the entire system at the wide-angle end in the state of being in focus on an infinite object is fw,
0.35 <Bfw / fw <0.55 (14)
The zoom lens according to any one of claims 1 to 17, which satisfies the conditional expression (14) represented by. The zoom lens according to any one of claims 1 to 18, wherein the subsequent group includes a lens group fixed to the image plane at the time of scaling to the image side most. An image pickup apparatus comprising the zoom lens according to any one of claims 1 to 19.

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